New virus to hit immune rabbits
A new rabbit virus strain set to be introduced to Marlborough next year is expected to put a dent in feral rabbits building immunity to previous strains.
Marlborough District Council biosecurity co-ordinator Jono Underwood said the council was waiting for approval to release the rabbit haemorrhagic disease virus (RHD) K5 strain in the region by autumn next year.
The council was among local authorities working with the Ministry of Primary Industries for a nationwide release of the virus next year.
The K5 strain was expected to remove 20-30 per cent of a rabbit population which had built up an immunity to the original calicivirus strain illegally released in 1997, Underwood said.
‘‘It won’t have the effect of having a big knock down of the rabbit population in Marlborough but will act more as a control method,’’ he said.
About 10 years after RHD virus was introduced rabbits began to show immunity after a good strike rate initially and poisoning was resumed.
Landcare Research scientists reported the RHD virus was still killing rabbits but not as effectively.
‘‘Rabbits are not currently a big pest problem in Marlborough and there are only isolated pockets, such as parts of the high country, where there the numbers are more prolific,’’ Underwood said.
Underwood said the K5 strain was not readily available to local authorities until it was first registered under the Agricultural Compounds and Veterinary Medicines Act and need to be approved by the Environmental Protection Authority before it could be applied under a national release strategy project.
Once approval was given the virus strain would be released to specific sites where numbers were higher before being distributed naturally to wider populations, he said.
Routine monitoring would help detect if the K5 strain becomes established as the dominant virus strain in the region.
Underwood said it was important that the release of the K5 virus was tightly controlled to avoid any repeat when its predecessor RHD was illegally introduced in the 1990s.